Pneumatic pump



Sept. 14, 1937. F. H. sLEEPER PNE'UMATIC PUMP Filed July 30, 1956 Patented Sept. 14, 1937 UNITED VSTATES PNEUMATIC rUMP Frank H. Sleeper, St. Petersburg,

to Sleeper & Hartley,

Fla., assignor Y Incorporated, Worcester,

Mass., a corporation of Massachusetts Application July so, 1936, serial No. 93,5151'V 3 Claims. (Cl. 2304157) This invention relates to a pneumatic pump o-ry compressor, and more particularly to a device of f, this type having a cylindrical casing and a smaller p cylinder eccentrically rotatable therein and forming a crescent shaped space within which a vane is arranged to sweep the gas from an inlet to an outlet in the casing.

Pneumatic pumps of this type as heretofore proposed have been either complicated in construction or inefficient in operation or expensive to manufacture and maintain in service; and the necessity for overcoming excessive wear or for preventing leakage of gas between'relatively movn able parts has renderedV any high speed and effi- T cient operation impractical in cases where the increased frictional Wear has served detrimentally to accentuate the inherent constructional dis- Y advantages.

In accordance with my invention, I propose to make an air pump of this type which is so constructed that gas seals or especially constructed wear receiving parts are not needed, and the pump may operate on the principle that gas leakage between relatively movable parts is rendered innocuous by a rapid revolution of the vane.

The primary object of this invention is to provide a pneumatic pump of this type which is especially adapted for high speed operation and will give a long life of useful service, and in particular to so construct and arrange the parts as to provide the minimum of frictional wear and to obviate the necessity for providing air seals between relatively movable parts. Further objects and advantages in the constructional features of my invention will be apparent in the following disclosure.

In order that the invention may be more fully understood reference is to be had to the accompanying drawing which illustrates one embodiment of this invention, and wherein:V

Fig. 1 is a vertical longitudinal section through the apparatus;

Fig. 2 is a transverse section on theline 2 2 of Fig; l, looking in the direction of the arrows 'and Figs. 3, 4, and 5are diagrammatic views corresponding with Fig. 2, but with parts omitted, which illustrate the operation of the device.

I'he pneumatic compressor or pump as illustrated comprises a cylindrical casing within which is Ytangentially mounted a smaller hollow rotatable cylinder having a slot through its peripheral wall so arranged that a vane projecting through the slot may be revolubly mounted within the cylinder and serve to sweep gas within the space between the cylindrical surfaces froman inlet'to an outlet, both of which are arranged in the peripheral wall of the casing. 'I'he casing, which provides thev inner cylindrical wall I0, cornprises a removable end wall I2 closing the open 5 end of a cup shaped body I4, which has a long boss or lateral extension I6 adapted to carry a spindle and its bearings. Rotatably mounted within a recess I8 vin th vertical inner wall of the casing 'is a further cup 10 shaped hollow cylinder 2,0. The outerl periphery Yof this cup is tangential to the bottom portion of ,the inner peripheral wall I0, and the latter is preferably recessed slightly,`as by a ygrinding operation, so thatrthe outside surface of the cup` Vl5 20 contacts throughout a wide arc With the'bottorn portion 22 of the wall I0, as Villustrated in Fig. 2. It is preferred that these two parts makev a close t throughoutthe 'entire are between a gas inlet 24 and a gas outlet 26 formed in the 20 peripheral wall o-f the casing I4 and so insure that no gas may be pocketed between the outlet and the inlet. lEach of these ports 24 and 26 is shaped as a long slot extending substantially parallel with the center line ofthe cylinder IIJ. f The 25 cup or cylinder l2l) has its inner wall 28 lying ush with Yor in the plane of the inner wall of the casing. v'I'heopposite annular face 32 of the cup has a sliding contact with the plane vertical inner face 34 of the end wall I2. Thus, a 30 closed crescent shaped gas chamber 36 is formed between the outer wall of the cup 20 and the inner cylindrical wall I0 of the casing. 7

The cup 20 has a slot 38 (Fig. 2) extending the length of its inner peripheral wall and parallelY with its axis o-f rotation. A vane 40, which is arranged torevolve about the axis or center line of the cylinder I0, is. suitably mounted on a driving shaft 42 projecting through a central opening in the casing wall l2 into the hollow space 40 of the cupV 20. 'Ihis vane 40 is slidable throughthe slot 38. of the cup 20 and is of such dimensions that it makes a bearing contact with the inner walls I0, 38, and 34 of the outer casing and thus may drive the gas ahead of it when revolv- 45 ing. 'Ihe slot 38 is sufficiently wideand its edge faces are rounded, as shown in Fig. 2, so as to provide freedom of motion for the gas driving vane and toform adequate bearing surfaces of low frictional wear. The vaner4ll may be suit- 50 ably secured to the shaft 42, such as by being inserted in a slot milled in the inner end portion of the shaft and fastened into the slot by means of pins 44. Acounterweight 46 suitably secured onthe'opposite side of the shaft insures rotation 55 of the vane and shaft without unnecessary vibration.

It will now be appreciated that the vane 40 when in certain positions cuts the crescent shaped space 36 into two parts, one of which communicates with the inlet opening 24 and the other with the outlet opening 26, so that as the vane sweeps around in the direction of the arrow it will serve to force the gas ahead of it towards the outlet 26 while further gas will be drawn in through opening 24 to ll the space in the rear of the vane. The opening 24 may communicate directly with the outside air or other-source of gas supply for this purpose. The crescent shaped chamber 36 is made as large as isconsistent with the design of the pump; hence the cylinder 20 is to be materially smaller than the inner cylinder I0, as illustrated.

The cup or inner cylinder 26 is so mounted that it may rotate freely under the impulse of the vane 40 which acts as a driving member therefor. One suitable mounting for the cup 26 comprises a long, shaft B extending laterally from the side of thecup and through the hollow hub I6 with its axis spaced from but parallel with the axis of the cylinder Ill. Ball bearings support the ends of the shaft, which comprise inner raceways 52 and 54 slidably fitted on the shaft 50 for rotation therewith and outer raceways 56 and 58 mounted in suitable recesses in the extension boss I6. A nut 60 threaded on the reduced inner end of the sha-ft 50 serves to hold the Yball raceway 52 in position against a shoulder on the shaft. A cap 62 suitably secured to the hub I6,

j -as by cap screws, serves to hold the outer ball raceway 56 in place and to provide a closure for grease for the bearings. The ball bearings 54, 58 may be suitably fitted in position at the other end of the shaft. The construction of these parts may, of course, be as desired, and suitable provisions may be made for locating the shaft and the cup properly within the casing. Various other arrangements may be adopted as desired for mounting the inner cylinder 20 and permitting free rotation under the driving force of the vane 40.

The driving shaft 42 which rotates about the axis of the cylinder I0 and carries the vaney 40 may be driven by any suitable device, but is shownras driven by a gear 64 keyed to the outer end of the shaft and adapted to be rotated by a high speed power mechanism, such as a large gear on an electric motor spindle. The shaft 42 may have an enlarged portion or ange` 66 slidably tting within a cylindrical opening in the casing wall I2, and the inner surface of the flange serves as a gauge for locating the vane 40 in operative association with the inner wall 34 of the casing. The shaft 42 is mounted at one end onY the wall I2 and at the other on an up-V right arm 61. For this purpose, ball bearings are provided and may comprise an inner raceway 68 held against the flange 66 by a nut 'I0 threaded on the shaft. The outer raceway 12 of the bearing is set within a recess in the wall I2,-

and the bearings are protected by means of the grease cap 14 secured to the wall I2 by cap screws. The outer end of the shaft 42 is likewise mounted in ball bearings comprising the inner raceway 'I6 and an outer raceway 'I8 protected by a grease cap 8D. A sleeve 82 engaging the rear of the gear 64 serves to hold the inner raceway 16 nxedly in position against a shoulder on the shaft.

When the gear 64 isrotated at a suitable high speed, the driving shaft 42 causes the vane 40 to move in the direction of the arrow and to engage the right hand edge of the slot 38 (Fig. 2) and thus revolve the cylinder 20 within the casing Ill. The air inlet 24 is a longitudinal slot extending lengthwise of the casing I6 and has free communication with the outside atmosphere in the device illustrated. Hence, as the vane 4U passes from the position shown in Fig. 3 across the opening of the slot 24 andthrough the successive positions shown in Figs 2 and 4, this vane will drive the air towards the outlet opening 26 and at the sam-e time cause air to enter in the rear of the vane and again fill the inlet portion of the crescent shaped chamber 36. The high speed vane 46 therefore sweeps the air intermittently towards the opening 26 and outwardly through the passage 84 in the plate 86 to a ta-nk or pipe line or any other construction adapted to receive the air under pressure.

.When the vane 40 passes from. the position shown in Fig. 4 to that of Fig. 5, theair might escape backwards through the outlet opening 26 and the crescent shaped chamber to the inlet 24 except for a check valve arranged to prevent the same. Any suitable construction may be adopted for this purpose but as shown in Fig. 2, the valve may comprise a flap 90 pivoted within a recess in the plug 92 which isy in turn secured in the casing wall by the plate 86. This ap extends across the opening 26 and serves effectively to prevent any backward movement of air therethrough. It is forced against its seat by means of a spring pressed plunger 94 held in position by a spring 66 of suitable strength to holdthe valve in place but permit it to' open freely under the pressure of the gas in advance of the vane. A V-shaped recess 98 is cuil in the casing wall II)Y adjacent to the outlet opening 26, and this recess is so shaped that as the vane 40 sweeps past the position shown in Fig. 4, not air will be pocketed in the small space between the vane and the two cylinder walls.

In this construction, the eccentrically mounted cylinder is freely rotated by the driving force of the vane 40. The contact between the vane 40 and the adjacent wall of the slot 38 serves to prevent escape of air backwards into the inner space of the cup 2D and thus through the slot opening to the inlet opening 24. The inner space of this cup 26 is always in communication with the air from the inlet 24 which lls the lefthand portion of the crescent shaped chamber,'but the tight frictional fit between the vane 4D and the wall 38 prevents loss of air through this inner chamber. Any frictional wear between the vane 40 and the edge of the slot 3B merely serves to maintain this air seal effectively. There is no other part where excessive frictional wear can take place.

An important feature of this construction lies in having the inlet and the outlet openings in the peripheral wall of the casing and thus communicating directly with the crescent shaped space 36. This simple arrangement makes it unnecessary to provide air seals or especially constructed sliding contact members or valves to insure the proper passage of air through the device.V Since the inner space within the cylinder 26 is' in free communication with the air under atmospheric pressure in the left hand portion of the crescent space`36, then no provision needs to be made to control the flow of air between these two spaces. The only valve required is the spring pressed valve 90 to prevent the backward flow of air through the pump, and the various parts need to be given only a reasonably tight sliding fit to insure an eiicient movement of air through the device. By having the vane and the cylinder cup mounted on separate shafts and by having the shafts long and adequately supported on ball bearings, as illustrated, the parts of the device of the pump may be fitted together accurately and maintained in a proper operative relationship throughout a long life of service. This pump, therefore, as constructed will serve to force air intermittently to a desired pressure system, and when associated with a small pressure tank it will provide a supply of air under substantially constant pressure for use as desired.

It is to be understood that the mechanism has been illustrated in the drawing in a somewhat diagrammatic fashion in order to clarify the description of the invention, but the various parts may be made in suitable shapes and sizes as is consistent with good machine design practice. In view of the above disclosure, many modifications will be apparent as residing within the scope of the invention covered by the appended claims.

Having thus described my invention, what I claim as' new and desire to secure-'by Letters Patent is:

1. A pneumatic Vpump comprising a casing having end walls and a peripheral wall providing an inner substantially cylindrical surface having spaced inlet and outlet ports opening directly therethrough, a small hollow cylinder eccentrically mounted within the casing and contacting with the inner cylindrical surface between the ports and thereby forming a crescent shaped space communicating at its ends directly with said ports, a freely rotatable shaft projecting through one end wall of the casing and serving as the sole rotatable support for said inner cylinder, a driving shaft axially parallel with the other shaft and concentric with the lcasing which projects through the opposite end wall thereof, radial and end thrust bearings for each of the shafts which locate the supported parts, said inner cylinder having a slot parallel with its axis, a vane xedly and radially mounted on the driving shaft which projects freely through and slidably contacts with one edge of said slot and forms an air seal therewith and which cooperates with the walls of the crescent space to drive gas from the inlet towards the outlet port, and a check valve to prevent the reverse flow of the gas through the outlet towards the inlet.

2. A pneumatic pump comprising a casing having end walls and an inner substantially cylindrical wall provided with spaced inlet and outlet Vslot in the Ainner cylinder but IIthe Walls of the crescent ports opening directly therethrough, a long driving shaft projecting through one end wall and axially concentric with the casing, a long driven shaft parallel with the first-shaft and spaced axially therefromwhich projects through the opposite end wall, radial and end thrust bearings supporting the opposite ends of and locating the shafts, an inner open ended, cup shaped cylinder |V mounted at its closed end on and rotatable with said driven shaft, said cylinder having a slot in its peripheral wall parallel with its axis and contacting extensively with the 'casing Wall between the ports and thereby forming a crescent shaped space communicating at its ends directly with said ports, a vane fitting closely to the walls of the crescent space which is iixedly mounted on the driving shaft and passes loosely through the with one edge of the slot and thereby forms an air seal while permitting free communication between the inlet port and the space within the inner cylinder, means fastened to the driving shaft for rotating the same and causing the vaneY to rotate the inner cylinder'onV its axis and t0 sweep gas from the inlet towards the outlet port, and a 'check valve arranged to prevent a reverse flow of gas from the outlet towards the inlet.

3. A pneumatic pump comprising a casing shaped as an open ended cup having a xed end wall and an inner substantially cylindrical surface provided with inlet and outlet ports opening directly therethrough, an end-plate removably closing the cup, a hollow boss opening through the fixed end wall, radial and end thrust bearings therein, a freely rotatable shaft mounted in said bearings eccentrically of the casing, a cup shaped cylinder having a slot parallel with makes a sliding it I its axis and an end wall mounted on the shaftV i which is arranged to contact with theinnervsurface of the casing between'its ports and provide a crescent shapedspace communicating at its endsV with said ports, a driving shaft arranged Within and axially of the casing which passes through said end plate, radial and end thrust 'bearings Supporting the driving shaft, a vane fix- ?edly and radially mounted on the driving shaft and projecting loosely through but slidably contacting With one edge of the slot so as Vto form an air seal therewith, and which fits closely to space so as to force gas from the inlet towards the outlet port, said parts V being so arranged that the space within the inner cup communicates freely with the inlet port, and

a check valve in the outlet port to prevent a reverse flow of gas.

FRANK H. SLEEPER. 

